In vitro transformation of rabbit cytotrophoblast cells into syncytiotrophoblast: stimulation of hormone secretion by progesterone and dibutyryl cyclic 3',5'-adenosine monophosphate

• Published in: Biology of reproduction Vol. 52; no. 4; pp. 868 - 877
• Main Authors: Lee, V.H. (University of South Alabama, Mobile, AL.), Zhang, S.J, Chang, S.M.T, Fields, M.J, Fields, P.A
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01.04.1995
• Subjects: ADENOSINE MONOPHOSPHATE; ADENOSINMONOFOSFATO; Animals; Biological and medical sciences; Bucladesine - pharmacology; Butyrates - pharmacology; Butyric Acid; Cell Nucleus - ultrastructure; Cells, Cultured; CITOPLASMA; CONEJO (ORYCTOLAGUS); CULTIVO DE CELULAS; CULTURE DE CELLULE; CYTOPLASME; Cytoplasmic Granules - ultrastructure; DIFERENCIACION CELULAR; DIFFERENCIATION CELLULAIRE; Embryology: invertebrates and vertebrates. Teratology; Endoplasmic Reticulum - ultrastructure; ESTRUCTURA CELULAR; Female; Fetal membranes; Fundamental and applied biological sciences. Psychology; General aspects. Development. Fetal membranes; HORMONAS; HORMONE; Immunohistochemistry; IMMUNOLOGIE; INMUNOLOGIA; LAPIN (ORYCTOLAGUS); Microscopy, Electron; Mitochondria - ultrastructure; ORGANITE CELLULAIRE; ORGANULOS CITOPLASMICOS; PLACENTA; Pregnancy; PROGESTERONA; PROGESTERONE; Progesterone - pharmacology; Rabbits; Relaxin - analysis; Relaxin - metabolism; RELAXINA; RELAXINE; SECRECION; SECRETION; STRUCTURE CELLULAIRE; Trophoblasts - drug effects; Trophoblasts - physiology; Trophoblasts - ultrastructure; ULTRAESTRUCTURA; ULTRASTRUCTURE; Relaxine; Trophoblaste; Fetal membrane; Cyclic AMP; Rabbit; Biosynthesis; Lagomorpha; In vitro; Ovarian hormone; Endocrine secretion; Pregnancy; Syncytium; Vertebrata; Mammalia; Placenta; Female; Progesterone; Sex steroid hormone
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod52.4.868

Rabbit placenta syncytiotrophoblast cells exhibit immunostaining for the hormone relaxin. The objectives of this study were to evaluate the ability of cultured rabbit trophoblast cells to secrete immunoreactive (IR) relaxin and then to study the effects of progesterone, which is essential for maintenance of the placenta and of pregnancy in the rabbit, on that secretion. On Day 1, both treated and untreated trophoblast cell cultures consisted of 90% relaxin-negative mononuclear cells (syncytiotrophoblast and fibroblast) and 10% relaxin-positive multinuclear cells (syncytiotrophoblast). Media from untreated cultures, collected throughout 9 days of culture, contained low but constant levels of relaxin. Electron microscopy studies indicated that relaxin was localized in dense granules of the multinuclear cells and that these cells formed by fusion of mononuclear cytotrophoblast. Progesterone treatment (40 and 80 ng/ml) increased (p 0.0001) media concentrations of relaxin, increased the number of desmosomes between cytotrophoblast cells (12 vs. 4 for controls on Day 5), and increased the percentage of multinuclear cells (73% of the cell population vs. 20% for controls on Day 7). Specificity of the progesterone effect was evaluated by treatment of cultures with dibutyryl cAMP (dbcAMP), insulin, hCG, estradiol-17 beta, prostaglandin E2, and prostaglandin F2 alpha. Only dbcAMP (2 mM and 4 mM) produced an increase (p 0.0001) in media concentrations of relaxin. These results indicate that, like the intact placenta, cultured cytotrophoblast cells fuse to form syncytiotrophoblast and that the latter contain IR relaxin